The present invention relates to the field of quality testing in telecommunication networks. More specifically, it pertains to a method and apparatus for testing and measuring transmission line parameters, such as the post-dial delay, the line rate, the noise level and the signal level, among others.
Within the Public Switched Telephone Network (PSTN), test and measurement systems are required to remotely and automatically test the network transmission lines, in order to monitor the quality of service provided by the network. Such systems are commonly referred to as Transmission Impairment Measurement Systems (TIMS). Standard, existing TIMS use dedicated originating and terminating devices to take the necessary measurements, whereby the TIMS user is required to control both ends of the circuit being tested.
The evolution of the telecommunication industry has brought about deregulation and globalization within the industry, where providers and vendors of telecommunication services are expanding their product and service offerings to gain market share in this new environment. A proliferation of new telecommunication carriers is emerging and it is now less likely that a particular carrier will own, and thus be in a position to control, a particular network circuit under test from end-to-end. In addition, a new trend is appearing whereby carriers are transiting via other carriers within a single telecommunication network.
Regardless of the changes affecting the telecommunication networks, the testing and measurement of the network transmission line parameters continues to be an important requirement, as quality assurance is and always will be an ongoing issue. Within a particular telecommunication network, an originating carrier would like to be able to evaluate the service level provided for by its new suppliers, over the various circuits in use. Unfortunately, existing TIMS"" may not be able to provide this evaluation capability, due to their dependence on both an originating and a terminating dedicated for performing the transmission line measurements and tests.
The background information herein clearly shows that there exists a need in the industry to provide an improved method and apparatus for testing and measuring transmission line parameters within a telecommunication network.
The invention provides a method for measuring a certain parameter of a voice transmission line including an echo canceler, said method comprising:
enabling said echo canceler; and
applying a signal to the transmission line to measure the certain parameter.
The invention is particularly useful in measuring at least one parameter of a voice transmission line that includes an echo canceler. Normally, echo cancelers are designed to acquire a disabled mode when they detect a signal on the transmission line of the type that could be used to effect measurements. Typically, such signal may be a digital signal issued by a modem. When the echo canceler is disabled, the measurements taken do not reflect the true behavior of the transmission line when a voice signal is transmitted over it. The present invention provides a method and an apparatus to enable the echo canceler so as to be able to effect more meaningful measurements.
As embodied and broadly described herein, the invention provides a measuring device for measuring a certain parameter of a voice transmission line including an echo canceler and a terminating device, the terminating device and said measuring device being capable of establishing a data communicative relationship by exchanging data over the voice transmission line, the echo canceler being capable of acquiring an enabled mode and a disabled mode, in the enabled mode the echo canceler performing echo cancellation on the voice transmission line, when in the disabled mode, the echo canceler being responsive to the terminating device and said measuring device co-acquiring first and second signal conditions, respectively to acquire the enabled mode, the terminating device manifesting a predetermined pattern of signal variations that includes the first signal condition, said measuring device including a signal processing unit coupled to the transmission line and being operative for:
observing said predetermined pattern of signal variations manifested by said terminating device and for establishing on the transmission line said second signal condition at a point in time such that the first and second signal conditions occur over a common time period, such that the echo canceler acquires the enabled mode; and
measuring the certain parameter.